Handheld tester for starting/charging systems

ABSTRACT

An improved hand held starting/charging system tester. According to one aspect of the present invention, the portable handheld tester includes a connector to which various test cables can be removably connected to the tester. Detection circuitry within the tester determines which of several types of test cable is connected to the tester before testing. According to another aspect of the present invention, the portable handheld tester includes an improved user interface that permits a user to review test data from previously performed tests and further permits a user to either skip a previously performed test (thereby retaining the previously collected data for that test) or re-do the test (thereby collecting new data for that test). According to yet another aspect of the present invention, the portable handheld tester that performs a more complete set of tests of the starting/charging system.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of and claims priority toco-pending, commonly assigned, U.S. patent application Ser. No.:09/813,104, filed on Mar. 19, 2001, which is hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates generally to the field ofelectronic testing devices, and more specifically to a handheld deviceused to test the starting/charging system of an internal combustionengine in a vehicle.

BACKGROUND OF THE INVENTION

[0003] Internal combustion engines typically include a starting/chargingsystem that typically includes a starter motor, a starter solenoidand/or relay, an alternator having a regulator (or other charger), abattery, and associated wiring and connections. It is desirable toperform diagnostic tests on various elements of starting/chargingsystems to determine whether they are functioning acceptably. It istypical during many such tests, e.g., starter tests, cranking tests,various regulator tests, etc., to adjust the operation of the vehiclewhile sitting in the driver's seat e.g., starting the engine, turninglights and other loads on and off, revving the engine to a specificnumber of revolutions per minute, etc. Thus, it is desirable, if notnecessary, to have one person sitting in the driver's seat during manystarter/charger tests to perform the tests. For other tests, e.g.,battery tests, the user need not necessarily be in the driver's seat.

[0004] Testers used to test the starting/charging system of an internalcombustion engine are known. For example, the KAL EQUIP 2882 DigitalAnalyzer and KAL EQUIP 2888 Amp Probe could be used together to performa cranking system test, a charging system test, an alternator conditiontest, and an alternator output test. The KAL EQUIP 2882 Digital Analyzeris a handheld tester. Other known testers capable of testing astarting/charging system include the BEAR B.E.S.T. tester and the SUNVAT 40 tester, both of which allowed a user to test the starter,alternator, etc. Other testers capable of testing a starting/chargingsystem exist. The aforementioned BEAR B.E.S.T. and the SUN VAT 40testers are not handheld testers; they are typically stored and used ona cart that can be rolled around by a user.

[0005] Additionally, some other handheld testers capable of testing astarting/charging system are known. These devices typically have limiteduser input capability (e.g., a few buttons) and limited displaycapability (e.g., a two-line, 16 character display) commensurate withtheir relatively low cost with respect to larger units. The knownhandheld starting/charging system testers have several drawbacks. Forexample, the user interface on such devices is cumbersome. Additionally,some handheld starting/charging system testers have been sold witheither a shorter (e.g., three feet) cable or a longer (e.g., fifteenfeet) cable. With the shorter cable, two people would typically performthe tests of the starting/charging system, with one person under thehood with the tester and one person sitting in the driver's seat toadjust the operation of the vehicle. The longer cable would permit asingle user to sit in the driver's seat to perform the tests and adjustthe operation of the vehicle, but the user would need to wind up thefifteen feet of cable for storage. Lugging around the wound coils of thelong cable becomes especially inconvenient when the user wants to usethe tester for a quick battery check, because the wound coils of cablecan be larger than the test unit itself. Additionally, the userinterface in such units is typically very cumbersome.

[0006] There is a need, therefore, for an improved handheld testercapable of testing a starting/charging system of an internal combustionengine.

SUMMARY OF THE INVENTION

[0007] The present invention is directed toward an improved hand heldstarting/charging system tester. According to one aspect of the presentinvention, the portable handheld tester comprises a connector to whichvarious cables can be removably connected to the tester. According toanother aspect of the present invention, the portable handheld testercomprises an improved user interface that permits a user to review testdata from previously performed tests and further permits a user toeither skip a previously performed test (thereby retaining thepreviously collected data for that test) or re-do the test (therebycollecting new data for that test). According to yet another aspect ofthe present invention, the portable handheld tester performs a morecomplete set of tests of the starting/charging system. For example, thehandheld portable tester preferably performs a starter test, threecharging tests, and a diode ripple test. According to still anotheraspect of the present invention, the portable handheld tester performsan improved starter test. More specifically to an implementation of thestarter test, the portable handheld tester performs a starter test inwhich the associated ignition has not been disabled, where a hardwaretrigger is used to detect a cranking state and then samples of crankingvoltage are taken until either a predetermined number of samples havebeen collected or the tester determines that the engine has started.

[0008] It is therefore an advantage of the present invention to providea portable handheld tester for a starting/charging system of an internalcombustion engine having a connector to which a test cable can beremovably connected to the tester.

[0009] It is also an advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine that permits different test cables (e.g., the cablesof FIGS. 5A, 7A, and 8) to be used with a single tester, therebyallowing a wider range of functions to be performed with the tester.

[0010] It is another advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine that permits an optional extender cable (e.g., theextender cable of cable of FIGS. 6A and 6B) to be used, thereby allowingthe tester to be used by one person sitting in a driver's seat for sometests, but allowing a shorter cable to be used for other tests.

[0011] It is a further advantage of this invention to provide a portablehandheld tester for a starting/charging system of an internal combustionengine that allows the tester to be stored separately from the cable.

[0012] It is yet another advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine that comprises an improved user interface.

[0013] It is still another advantage of the present invention to providea portable handheld tester for a starting/charging system of an internalcombustion engine that comprises an improved user interface in which auser can review test data from previously performed tests and in whichthe user can, for each previously performed test, either skip thatpreviously performed test or re-do the test.

[0014] It is another advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine that comprises an improved user interface in which auser can review test data from previously performed tests and in whichthe user can, for each previously performed test, either retain thepreviously collected data for that test or collect new data for thattest.

[0015] It is yet another advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine that performs a more complete set of tests of thestarting/charging system, preferably a starter test, three chargingtests, and a diode ripple test.

[0016] It is still another advantage of the present invention to providea portable handheld tester for a starting/charging system of an internalcombustion engine that performs an improved starter test, preferably inwhich a hardware trigger is used to detect a cranking state and thensamples of cranking voltage are taken until either a predeterminednumber of samples have been collected or the tester determines that theengine has started.

[0017] These and other advantages of the present invention will becomemore apparent from a detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the accompanying drawings, which are incorporated in andconstitute a part of this specification, embodiments of the inventionare illustrated, which, together with a general description of theinvention given above, and the detailed description given below, serveto example the principles of this invention, wherein:

[0019]FIG. 1A is an isometric view of an embodiment of thestarting/charging system tester according to the present invention;

[0020]FIG. 1B is a high-level block diagram showing an embodiment of thestarting/charging system tester according to the present invention;

[0021]FIG. 2 is a medium-level block diagram showing a detection circuitand a test circuit of an embodiment of the starting/charging systemtester according to the present invention;

[0022]FIG. 3A is a schematic block diagram showing more detail about oneimplementation of a detection circuit according to the presentinvention;

[0023] FIGS. 3B-3F are schematic diagrams showing equivalent circuits ofa portion of the detection circuit of FIG. 3A showing the detectioncircuit of FIG. 3A in various use configurations;

[0024]FIG. 4A is a schematic block diagram showing more detail about oneimplementation of a voltmeter test circuit of the starting/chargingsystem tester according to the present invention;

[0025]FIG. 4B is a schematic block diagram showing more detail about oneimplementation of a diode ripple test circuit of the starting/chargingsystem tester according to the present invention;

[0026]FIG. 4C is a schematic diagram illustrating a test currentgenerator circuit of the battery tester component of the presentinvention;

[0027]FIG. 4D is a schematic diagram illustrating the an AC voltageamplifier/converter circuit of the battery tester component of thepresent invention;

[0028]FIG. 5A shows a plan view of one implementation of a clamp cablefor the starting/charging system tester according to the presentinvention;

[0029]FIG. 5B shows a schematic diagram of connections within the clampcable of FIG. 5A;

[0030]FIG. 5C shows a rear view of the inside of the housing of theclamp cable of FIG. 5A;

[0031]FIG. 6A shows a plan view of one implementation of an extendercable for the starting/charging system tester according to the presentinvention;

[0032]FIG. 6B shows a schematic diagram of connections within theextender cable of FIG. 6A;

[0033]FIG. 7A shows a plan view of one implementation of a probe cablefor the starting/charging system tester according to the presentinvention;

[0034]FIG. 7B shows a schematic diagram of connections within the probecable of FIG. 7A;

[0035]FIG. 7C shows a rear view of the inside of the housing of theprobe cable of FIG. 7A;

[0036]FIG. 8 is a block diagram of a sensor cable, e.g., a currentprobe, for the starting/charging system tester according to the presentinvention;

[0037]FIG. 9 is a high-level flow chart showing some of the operation ofthe embodiment of the starting/charging system tester of the presentinvention;

[0038]FIG. 10 is a medium-level flow chart/state diagram showing theoperation of the test routine of the embodiment of the starting/chargingsystem tester of the present invention;

[0039] FIGS. 11A-11D are a low-level flow chart/state diagram showingthe operation of the test routine of the embodiment of thestarting/charging system tester of the present invention;

[0040]FIG. 12 is a low-level flow chart showing the operation of thestarter test routine of an embodiment of the starting/charging systemtester of the present invention; and

[0041]FIG. 13 shows a plurality of representations of screen displaysexemplifying an embodiment of a user interface according to the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0042] Referring to FIGS. 1A and 1B, there is shown a handheld, portabletester 10 according to the present invention for testing astarting/charging system 11. The tester 10 comprises a handheld,portable enclosure 12 housing an electronic circuit 14 that, among otherthings, tests the starting/charging system 11. One or more user inputs16, shown in FIG. 1A as four momentary switches implemented aspushbuttons 18-21, allow a user to interface with the tester 10. Adisplay 24, shown in FIG. 1A as a liquid crystal display (LCD) 26 havingfour lines of twenty characters each, allows the tester 10 to displayinformation to the user.

[0043] The tester 10 is placed in circuit communication with thestarting/charging system 11 via a cable 28. “Circuit communication” asused herein indicates a communicative relationship between devices.Direct electrical, electromagnetic, and optical connections and indirectelectrical, electromagnetic, and optical connections are examples ofcircuit communication. Two devices are in circuit communication if asignal from one is received by the other, regardless of whether thesignal is modified by some other device. For example, two devicesseparated by one or more of the following—amplifiers, filters,transformers, optoisolators, digital or analog buffers, analogintegrators, other electronic circuitry, fiber optic transceivers, oreven satellites—are in circuit communication if a signal from one iscommunicated to the other, even though the signal is modified by theintermediate device(s). As another example, an electromagnetic sensor isin circuit communication with a signal if it receives electromagneticradiation from the signal. As a final example, two devices not directlyconnected to each other, but both capable of interfacing with a thirddevice, e.g., a CPU, are in circuit communication. Also, as used herein,voltages and values representing digitized voltages are considered to beequivalent for the purposes of this application and thus the term“voltage” as used herein refers to either a signal, or a value in aprocessor representing a signal, or a value in a processor determinedfrom a value representing a signal. Additionally, the relationshipsbetween measured values and threshold values are not considered to benecessarily precise in the particular technology to which thisdisclosure relates. As an illustration, whether a measured voltage is“greater than” or “greater than or equal to” a particular thresholdvoltage is generally considered to be distinction without a differencein this area with respect to implementation of the tests herein.Accordingly, the relationship “greater than” as used herein shallencompass both “greater than” in the traditional sense and “greater thanor equal to.” Similarly, the relationship “less than” as used hereinshall encompass both “less than” in the traditional sense and “less thanor equal to.” Thus, with A being a lower value than B, the phrase“between A and B” as used herein shall mean a range of values (i)greater than A (in the traditional sense) and less than B (in thetraditional sense), (ii) greater than or equal to A and less than B (inthe traditional sense), (iii) greater than A (in the traditional sense)and less than or equal to B, and (iv) greater than or equal to A andless than or equal to B. To avoid any potential confusion, thetraditional use of these terms “greater than and “less than,” to theextent that they are used at all thereafter herein, shall be referred toby “greater than and only greater than” and “less than and only lessthan,” respectively.

[0044] Important with respect to several advantages of the presentinvention, the tester 10 includes a connector J1 to which test cable 28is removably connected. Having the test cable 28 be removably connectedto the tester 10 among other things (i) permits different test cables(cables of FIGS. 5A, 7A, and 8) to be used with a single tester therebyallowing a wider range of functions to be performed with the tester 10,(ii) permits an optional extender cable (cable of FIGS. 6A and 6B) to beused, thereby allowing the tester 10 to be used by one person sitting ina driver's seat for some tests, but allowing a shorter cable (FIG. 5A)to be used for others, and (iii) allows the tester 10 to be storedseparately from the cable.

[0045] Referring more specifically to FIG. 1B, the tester 10 of thepresent invention preferably includes an electronic test circuit 14 thattests the starting/charging system 11, which test circuit 14 preferablyincludes a discrete test circuit 40 in circuit communication with anassociated processor circuit 42. In the alternative, the test circuit 14can consist of discrete test circuit 40 without an associated processorcircuit. In either event, preferably, the tester 10 of the presentinvention also includes a detection circuit 44 in circuit communicationwith the test circuit 40 and/or the processor circuit 42. The testcircuit 40 preferably accepts at least one test signal 46 from thestarting/charging system 11 via the cable 28 and connector J1. Thedetection circuit 44 preferably accepts at least one detection signal 48from the tester cable 28 or other device (e.g., sensor cable of FIG. 8)placed in circuit communication with the tester 10 via connector J1.Tester 10 also preferably includes a power circuit 60 allowing thetester 10 to be powered by either the starting/charging system 11 viapower connection 61 or by an internal battery 62.

[0046] The processor circuit 42, also referred to herein as justprocessor 42, may be one of virtually any number of processor systemsand/or stand-alone processors, such as microprocessors,microcontrollers, and digital signal processors, and has associatedtherewith, either internally therein or externally in circuitcommunication therewith, associated RAM, ROM, EPROM, clocks, decoders,memory controllers, and/or interrupt controllers, etc. (all not shown)known to those in the art to be needed to implement a processor circuit.One suitable processor is the SAB-C501G-L24N microcontroller, which ismanufactured by Siemens and available from various sources. Theprocessor 42 is also preferably in circuit communication with variousbus interface circuits (BICs) via its local bus 64, e.g., a printerinterface 66, which is preferably an infrared interface, such as theknown Hewlett Packard (HP) infrared printer protocol used by manystandalone printers, such as model number 82240B from HP, and whichcommunicates via infrared LED 67. The user input 16, e.g., switches18-21, preferably interfaces to the tester 10 via processor 42.Likewise, the display 24 preferably is interfaced to the tester 10 viaprocessor 42, with the processor 42 generating the information to bedisplayed on the display 24. In addition thereto, or in the alternative,the tester 10 may have a second display 68 (e.g., one or more discretelamps or light emitting diodes or relays for actuation of remotecommunication devices) in circuit communication with the test circuit40.

[0047] Referring now to FIG. 2, a more detailed block diagram showing animplementation of the test circuit 40 and detection circuit 44 is shown.In the particular implementation of FIG. 2, the test circuit 40 anddetection circuit 44 are implemented using a digital-to-analog converter(DAC) 80 that is in circuit communication with processor 42 via bus 81and in circuit communication with a number of comparators 82 viareference voltage outputs 83, which comparators 82 in turn are incircuit communication with the processor 42 via test signals 85.Although the test circuit 40 and detection circuit 44 need not be soimplemented, having at least a portion of the test circuit 40 beimplemented using a DAC 80 and a comparator 82 in circuit communicationwith the processor 42 provides certain benefits, as explained below.

[0048] The detection circuit 44 preferably includes a detection frontend 84 and a comparator 82 a. The detection front end 84 preferablyaccepts as an input the detection signal 48 and generates an output 86to the comparator 82 a. Referring to FIG. 3A, a circuit implementationof the detection circuit 44 is shown schematically. The preferredimplementation of the detection front end 84 is shown as circuitry 90 tothe left of node 92. The circuitry shown includes a connection J1-6,J1-7, J1-8 to the battery of the starting/charging system 11, a PTC F2(positive temperature coefficient device that acts as a sort ofautomatically resetting fuse), a diode D7, a voltage divider created byresistors R14 and R15, and a connection to detection signal 48 at J1-4via resistor R29. The component values are preferably substantially asshown. Processor 42, via bus 81, causes DAC 80 to generate a particularvoltage on reference voltage line 83 a, which is input to comparator 82a. The detection front end 90 generates a particular detection voltageat node 92, depending on what signals are presented at power signal 61and detection signal 48. The comparator 82 a will output a logical ONEor a logical ZERO to processor 42 depending on the relative values ofthe reference voltage 83 a and the detection voltage at node 92. Thus,to detect which cable 28 or device is attached to connector J1, theprocessor 42 need only send a command to DAC 80 via bus 81, wait aperiod of time for the various voltages to stabilize, and read a binaryinput from input 85 a.

[0049] Various connection scenarios for detection front end circuitry 90are shown in FIGS. 3B-3F, which correspond to various test cables 28 andother signals connected to connector J1. In each, the voltage at node 92is determined using straightforward, known resistor equations, e.g.,resistor voltage divider equations, equivalent resistances for resistorsin series, and equivalent resistance for resistors in parallel, etc. InFIG. 3B, the power signal 61 is connected to the battery, which presentsa battery voltage V_(BATT), and the detection signal 48 (shown in FIG.3A) is left as an open circuit; therefore, the test voltage at node 92is approximately 0.1·V_(BATT), because the battery voltage V_(BATT) isdivided by resistors R14 (90.9 KΩ) and R15 (10.0 KΩ). In FIG. 3C, thepower signal 61 is connected to the battery, which presents a batteryvoltage V_(BATT), and the detection signal 48 is grounded to the batteryground; therefore, the test voltage at node 92 is approximately0.5·V_(BATT), because in this scenario the battery voltage is divided byR14 (90.9 KΩ) and the combination of R15 (10.0 KΩ) and R29 (10.0 KΩ) inparallel (5.0 KΩ combined resistance). In FIG. 3D, the power signal 61(shown in FIG. 3A) is left as an open circuit, and the detection signal48 is connected to an applied voltage V_(A); therefore, the test voltageat node 92 is ½V_(A), because the applied voltage V_(A) is dividedequally by resistors R29 (10.0 KΩ) and R15 (10.0 KΩ). In FIG. 3E, thepower signal 61 is connected to the battery, which presents a batteryvoltage V_(BATT), and the detection signal 48 is grounded to the batteryground via an additional resistor R29′; therefore, the test voltage atnode 92 is the following function of V_(BATT),$V_{92} = {\frac{{Re}\quad q}{{{Re}{\quad \quad}q} + R_{14}} \cdot V_{{BATT}}}$where${{Re}\quad q} = \frac{1}{\frac{1}{R15} + \frac{1}{{R29} + {R29}^{\prime}}}$

[0050] because in this scenario the battery voltage is divided by R14and the combination of R15 in parallel with R29 and R29′ in series,which is about 0.07·V_(BATT) if R29′ is 10.0 KΩ. Finally, in FIG. 3F,the power signal 61 (shown in FIG. 3A) is open circuit and the detectionsignal 48 (shown in FIG. 3A) is open circuit; therefore, the voltage atnode 92 is pulled to ground by resistor R15. In al these scenarios,power ground 94 is preferably connected to signal ground 96 either atthe negative battery terminal or within test cable 28. The processor 42,DAC 80, and comparator 82 a preferably use the known successiveapproximation method to measure the voltage generated by the detectioncircuit front end 84.

[0051] Thus, in the general context of FIGS. 1A, 1B, 2, and 3A-3F, aspecific test cable 28 connected to connector J1 will cause the voltage86 (i.e., the voltage at node 92) to be a specific voltage, which ismeasured using the successive approximation method. The processor 42then preferably determines from that voltage 86 which cable 28 isconnected to the tester at connector J1 and executes appropriate codecorresponding to the particular cable 28 connected to the connector J1.Various specific connectors 28 are described below in connection withFIGS. 5A-5C, 6A-6B, 7A-7C, and 8.

[0052] Referring back to FIG. 2, the test circuit 40 preferably includesa voltmeter circuit 100 and a diode ripple circuit 102. The voltmetercircuit 100 is preferably implemented using a DAC 80 and comparator 82b, to facilitate testing the starting portion of the starting/chargingsystem 11. In the preferred embodiment, the voltmeter circuit 100comprises an autozero circuit 104 in circuit communication with a signalconditioning circuit 106. The autozero circuit 104 preferably accepts asan input the test signal 46. The signal conditioning circuit 106generates a test voltage 107 that is compared to a reference voltage 83b by comparator 82 b, which generates test output 85 b. Similarly, thediode ripple circuit 102 is preferably implemented using a DAC 80 andcomparator 82 c. In the preferred embodiment, the diode ripple circuit102 comprises a bandpass filter 108 in circuit communication with asignal conditioning circuit 110, which in turn is in circuitcommunication with a peak detect circuit 112. The diode ripple circuit102 accepts as an input the test signal 46. The peak detect circuit 112generates a test voltage 114 that is compared to a reference voltage 83c by comparator 82 c, which generates test output 85 c.

[0053] Referring now to FIG. 4A, a schematic block diagram of apreferred embodiment of the voltmeter circuit 100 is shown. The signalconditioning circuit 106 preferably comprises a protective Zener diodeZ4 and amplifier circuit 115. Amplifier circuit 115 preferably comprisesan operational amplifier U8-A and associated components resistor R16,resistor R20, capacitor C21, capacitor C45, and diode D12, connected incircuit communication as shown. Amplifier circuit 115 generates testsignal 107 as an input to comparator 82 b. The processor 42, DAC 80,amplifier circuit 115, and comparator 82 b preferably use the knownsuccessive approximation method to measure the voltage input to theamplifier 115, which is either the signal 46 or a ground signalgenerated by the autozero circuit 104 responsive to the processor 42activating transistor Q1. After using the successive approximationmethod, the processor 42 has determined a value corresponding to andpreferably representing the voltage at 46. The autozero circuit 104preferably comprises a transistor Q1 in circuit communication withprocessor 42 via an autozero control signal 116. Ordinarily, the signal46 from cable 28 passes through resistor R26 to amplifier 115. However,responsive to the processor 42 asserting a logical HIGH voltage(approximately 5 VDC) onto the autozero control signal 116, transistorQ1 conducts, causing the signal 46 to be pulled to signal ground 96through resistor R26. As known to those in the art, the voltage measuredat signal 107 while the autozero control signal 116 is asserted is usedas an offset for voltage measurements taken with voltmeter 100 and isused to offset the value corresponding to and preferably representingthe voltage at 46.

[0054] Having the voltmeter 100 be implemented in this manner, i.e.,with a processor, a DAC, and a comparator, provides several benefits.One benefit is reduced cost associated with not having to have adiscrete analog-to-digital converter in the circuit. Another benefit isdemonstrated during the test of the starting portion of thestarting/charging system 11. In that test, the test circuit 40 waits forthe battery voltage to drop to a predetermined threshold value, whichindicates that a user has turned the key to start the starter motor. Thevoltage drops very rapidly because the starter motor presents almost ashort circuit to the battery before it begins to rotate. The particularimplementation of FIG. 4A facilitates the process of detecting thevoltage drop by permitting the processor 42 to set the threshold voltagein the DAC 80 once and then continuously read the input port associatedwith input 85 b from comparator 82 b. As the battery voltage drops tothe threshold voltage set in DAC 80, the output comparator almostinstantaneously changes, indicating to processor 42 that the voltagedrop has occurred.

[0055] Referring now to FIG. 4B, a schematic block diagram of the dioderipple circuit 102 is shown. As discussed above, in the preferredembodiment, the diode ripple circuit 102 comprises a bandpass filter 108in circuit communication with a signal conditioning circuit 110, whichin turn is in circuit communication with a peak detect circuit 112. Thebandpass filter 108 preferably comprises operational amplifier U14-A andassociated components—resistor R46, resistor R47, resistor R48,capacitor C40, capacitor C41, and Zener diode Z1—connected as shown.Zener diode Z1 provides a pseudo-ground for the AC signal component ofsignal 46. The bandpass filter 108 has a gain of approximately 4.5 andhas bandpass frequency cutoff values at approximately 450 Hz and 850 Hz.Signal 109 from bandpass filter 108 is then conditioned using signalconditioner 110. Signal conditioner 110 preferably comprises anamplifier U14-B and a transistor Q10 and associated components—resistorR11, resistor R47, resistor R49, resistor R50, and Zener diodeZ1—connected as shown. Signal conditioner circuit 110 generates a DCsignal 111 corresponding to the amplitude of the AC signal component ofsignal 46. The resulting signal 111 is then input to peak detector 112,preferably comprising diode D9, resistor R51, and capacitor C42,connected as shown, to generate signal 114. The signal 114 from the peakdetect circuit 112 is measured by the processor 42, DAC 80, andcomparator 82 c using the successive approximation method. This value iscompared to a threshold value, preferably by processor 42, to determineif excessive diode ripple is present. An appropriate display isgenerated by the processor 42. In the alternative, the signal 85 c canbe input to a discrete display to indicate the presence or absence ofexcessive diode ripple.

[0056] Referring once again to FIG. 2, test circuit 40 further has abattery tester component 117. The battery tester component 117 includesa test current generator circuit 118 and an AC voltageamplifier/converter circuit 119. The battery tester component 117 ispreferably implemented using DAC 80 and a comparator 82 d, to facilitatethe testing of a battery. The test current generator circuit 118preferably applies a load current to the battery under test. The ACvoltage amplifier/converter circuit 119 measures the voltage generatedby the load current applied to the battery. The measuring preferablyincludes amplifying the voltage and converting it to a ground referencedDC voltage.

[0057] In this regard, reference is now made to FIG. 4C where thepreferred embodiment of test current generator circuit 118 isillustrated. The circuit 118 includes resistors R21, R22, R27, R28, R36,R37, R40, and R42, capacitors C24, C28, C29, and C33, operationalamplifiers U10-A and U10-B, and transistors Q6, Q8, and Q9, allinterconnected as shown. In operation, processor 42 and DAC 80 togetherproduce a variable voltage pulse signal that is output on node 122. Afilter is formed by resistors R28, R27, R36, capacitors C24 and C28 andamplifier U10-B, which converts the signal on node 122 to a sine wavesignal. The sine wave signal is applied to a current circuit formed byamplifier U10-A, R22, C29, Q6, Q8, and R40 arranged in a current sinkconfiguration. More specifically, the sine wave signal is applied to the“+” terminal of amplifier Q10-A. The sine wave output of amplifier ofQ10-A drives the base terminal of Q6 which, in turn, drives the baseterminal of Q8 to generate or sink a sine wave test current. This causesthe sine wave test current to be applied to the battery under testthrough terminal 61 (+POWER). It should also be noted that anenable/disable output 121 from processor 42 is provided as in inputthrough resistor R36 to amplifier U10-B. The enable/disable output 121disables the test current generator circuit 118 at start-up until DAC 80has been initialized. Also, a surge suppressor F2 and diode D7 areprovided to protect the circuitry from excessive voltages and currents.As described above, the test current generates a voltage across theterminals of the battery, which is measured by AC voltageamplifier/converter circuit 119. This AC voltage is indicative of thebattery's internal resistance.

[0058] Referring now to FIG. 4D, AC voltage amplifier/converter circuit119 will now be discussed in more detail. The circuit is formed of twoamplifier stages and a filter stage. The first amplifier stage is formedby diodes D3 and D5, resistors R30, R31, R32, R33, R34, amplifier U9-A,and zener diode Z5. The second amplifier stage is formed by resistorsR9, R24, R25, and R17, capacitor C27, amplifier U9-B, and transistor Q4.The filter stage is formed by resistors R8, R18, R19, capacitors C15,C17, and C19, and amplifier U7-A.

[0059] In operation, the AC voltage to be measured appears on node 46(+SENSE) and is coupled to amplifier U9-A through C32, which removes anyDC components. An offset voltage of approximately 1.7 volts is generatedby resistors R33 and R34 and diodes D3 and D5. Resistor R32 and zenerdiode Z5 protect amplifier U9-A against excessive input voltages. Thegain of amplifier U9-A is set by resistors R30 and R31 and isapproximately 100. Hence, the amplified battery test voltage is outputfrom amplifier U9-A to the second amplifier stage.

[0060] More specifically, the amplified battery test voltage is inputthrough capacitor C27 to amplifier U9-B. Capacitor C27 blocks any DCsignal components from passing through to amplifier U9-B. Resistors R9and R25 and zener diode Z3 bias amplifier U9-B. Coupled between theoutput and (−) input of amplifier U9-B is the emitter-base junction oftransistor Q4. The collector of Q4 is coupled to the ground bus throughresistor R17. In essence, the second amplifier stage rectifies thedecoupled AC signal using amplifier U9-B and transistor Q4 to invertonly those portions of the decoupled AC signal below approximately 4.1volts and referencing the resulting inverted AC signal, which appearsacross R17, to the potential of the ground bus. The resulting AC signalis provided downstream to the filter stage.

[0061] Input to the filter stage is provided through aresistor-capacitor networked formed by resistors R18, R19, and R8, andcapacitors C17 and C19. Amplifier U7-A and feedback capacitor C15convert the AC input signal at the (+) input of the amplifier U7-A to aDC voltage that is output to node 120. Node 120 provides the DC voltageas an input to the (−) terminal of comparator 82 d. The (+) terminal ofcomparator 82 d receives the output of DAC 80 on node 83 d. The outputof comparator 82 d is a node 85 d that is in circuit communication withan data input on processor 42. Through DAC 80 and comparator 82 d,processor can use a successive approximation technique to determine theamplitude of the DC voltage on node 120 and, therefore, ultimately theinternal resistance of the battery under test. This internal resistancevalue, along with user input information such as the battery'scold-cranking ampere (hereinafter CCA) rating, can determine if thebattery passes or fails the test. If the battery fails the test,replacement is suggested. Additional battery tester circuitry can befound in U.S. Pat. Nos. 5,572,136 and 5,585,728, which are hereby fullyincorporated by reference.

[0062] Referring now to FIGS. 5A-5C, a two-clamp embodiment 128 of atest cable 28 is shown. The cable 128 of this embodiment preferablycomprises a four-conductor cable 130 in circuit communication with aconnector 132 at one end, connected as shown in FIGS. 5B and 5C, and incircuit communication with a pair of hippo clips 134, 136 at the otherend. The cable 128 is preferably about three (3) feet long, but can bevirtually any length. The connector 132 mates with connector J1 oftester 10. The four conductors in cable 130 are preferably connected tothe hippo clips 134, 136 so as to form a Kelvin type connection, withone conductor electrically connected to each half of each hippo clip,which is known in the art. In this cable 128, the power ground 94 andsignal ground 96 are preferably connected to form a star ground at thenegative battery terminal. Resistor R128 connects between the +sense and−sense lines. In test cable 128, pin four (4) is open; therefore, theequivalent circuit of the detection circuit 44 for this cable 128 isfound in FIG. 3B. More specifically, with the hippo clips 134, 136connected to a battery of a starting/charging system 11, and connector132 connected to mating connector J1 on tester 10, the equivalentcircuit of the detection circuit 44 for this cable 128 is found in FIG.3B. The processor 42 determines the existence of this cable 128 by (i)measuring the battery voltage V_(BATT) using voltmeter 100, (ii)dividing the battery voltage V_(BATT) by ten, and (iii) determining thatthe voltage at node 92 is above or below a threshold value. In thisexample the threshold value is determined to be approximately two-thirdsof the way between two expected values or, more specifically,(V_(BATT)/20+V_(BATT)/10.5)/1.5. If above this value, then cable 128 isconnected.

[0063] Referring now to FIGS. 6A-6B, an embodiment of an extender cable228 is shown. The cable 228 of this embodiment preferably comprises afour-conductor cable 230 in circuit communication with a first connector232 at one end and a second connector 234 at the other end, connected asshown in FIG. 6B. The cable 128 is preferably about twelve (12) feetlong, but can be virtually any length. Cable conductors 230 a and 230 bare preferably in a twisted pair configuration. Cable conductor 230 d ispreferably shielded with grounded shield 231. Connector 232 mates withconnector J3 of tester 10. Connector 234 mates with connector 132 ofcable 128 of FIGS. 5A-5C (or, e.g., with connector 332 of cable 328(FIGS. 7A-7C) or with connector 432 of cable 428 (FIG. 8)). In cable228, the power ground 94 and signal ground 96 are not connected to forma star ground; rather, the extender cable 228 relies on another testcable (e.g., cable 128 or cable 328 or cable 428) to form a star ground.In cable 228, pin four (4) of connector 232 (detection signal 48 in FIG.3A) is grounded to signal ground 96 (pin eleven (11)) via connection236; therefore, the equivalent circuit of the detection circuit 44 forthis cable 128 is found in FIG. 3C. More specifically, with a cable 128connected to connector 234, and with the hippo clips 134, 136 of cable128 connected to a battery of a starting/charging system 111, andconnector 232 connected to mating connector J1 on tester 10, theequivalent circuit of the detection circuit 44 for this cablecombination 128/228 is found in FIG. 3C. The processor 42 determines theexistence of this cable 128 by (i) measuring the battery voltageV_(BATT) using voltmeter 100, (ii) dividing the battery voltage V_(BATT)by twenty and, (iii) determining that the voltage at node 92 is above orbelow a threshold value. In this example the threshold value isdetermined to be approximately two-thirds of the way between twoexpected values or, more specifically, (V_(BATT)/20+V_(BATT)/10.5)/1.5.If below this value, then cable 128 is connected.

[0064] In response to detecting an extended cable combination 128/228,the processor 42 may perform one or more steps to compensate theelectronics in the test circuit for effects, if any, of adding thesignificant length of wiring inside cable 228 into the circuit. Forexample, voltage measurements taken with voltmeter 100 might need to bealtered by a few percent using either a fixed calibration value used forall extender cables 228 or a calibration value specific to the specificcable 228 being used. Such a calibration value might take the form of anoffset to be added to or subtracted from measurements or a scalar to bemultiplied to or divided into measurements. Such alterations could bemade to raw measured data or to the data at virtually any point in thetest calculations, responsive to determining that the extender cable 228was being used.

[0065] Referring now to FIGS. 7A-7C, a probe embodiment 328 of a testcable 28 is shown. The cable 328 of this embodiment preferably comprisesa two-conductor cable 330 in circuit communication with a connector 332at one end, connected as shown in FIGS. 7B and 7C, and in circuitcommunication with a pair of probes 334, 336 at the other end. The cable328 is preferably about three (3) feet long, but can be virtually anylength. The connector 332 mates with connector J1 of tester 10. In thiscable 328, the power ground 94 and signal ground 96 are connected byconnection 338 inside housing 340 of connector 332 to form a star groundinside housing 340. In cable 328, the battery power signal 48 is openand the detection signal 61 (pin four (4) of connector J1) is open;therefore, the equivalent circuit of the detection circuit 44 for thiscable 328 is found in FIG. 3F. More specifically, with connector 332connected to mating connector J1 on tester 10, the equivalent circuit ofthe detection circuit 44 for this cable 328 is found in FIG. 3F, i.e.,the voltage at node 92 is at zero volts or at about zero volts. Theprocessor 42 determines the existence of this cable 328 by (i) measuringthe battery voltage V_(BATT), (ii) dividing the battery voltage V_(BATT)by a predetermined value such as, for example, ten or twenty, and (iii)determining that the voltage at node 92 is above or below a thresholdvalue.

[0066] The power circuit 60 allows the tester 10 to power up using theinternal battery 62 when using the cable 328 with probes. Morespecifically, pressing and holding a particular key, e.g., key 21,causes the internal battery 62 to temporarily power the tester 10.During an initial start-up routine, the processor determines the batteryvoltage using voltmeter 100 and determines that there is no batteryhooked up via power line 61. In response thereto, the processor 42 viacontrol signal 63 causes a switch, e.g., a MOSFET (not shown) in powercircuit 60 to close in such a manner that the tester 10 is powered bythe internal battery 62 after the key 21 is released.

[0067] Referring now to FIG. 8, a block diagram of a proposed sensorcable 428 is shown. Sensor cable 428 is preferably an active, powereddevice and preferably comprises a four-conductor cable 430, a connector432, a power supply circuit 434, an identification signal generator 436,a control unit 438, a sensor 440, a pre-amp 442, and a calibrationamplifier 446, all in circuit communication as shown in FIG. 8.Connector 432 mates with connector J1 of tester 10. Sensor cable 428 mayor may not be powered by a battery being tested and may therefore bepowered by the internal battery 62 inside tester 10. Accordingly, sensorcable 428 preferably comprises battery power connections 430 a, 430 b tothe internal battery 62. Power supply circuit 434 preferably comprises apower regulator (not shown) to generate from the voltage of battery 62the various voltages needed by the circuitry in sensor cable 428. Inaddition, power supply circuit 434 also preferably performs otherfunctions of known power supplies, such as various protection functions.The sensor cable 428 also preferably comprises an identification signalgenerator 436 that generates an identification signal 430 c thatinterfaces with detection circuit 44 of tester 10 to provide a uniquevoltage at node 92 for this particular cable 428. Identification signalgenerator 436 may, for example, comprise a Zener diode or an activevoltage regulator (neither shown) acting as a regulator on the internalbattery voltage to provide a particular voltage at 430 c, therebycausing the detection circuit to behave as in FIG. 3D, with the voltageat node 92 being about half the voltage generated by identificationsignal generator 436. In the alternative, another circuit of FIGS. 3B-3Fmay be used to uniquely identify the sensor cable 428. Sensor cable 428is preferably controlled by control unit 438, which may be virtually anycontrol unit, e.g., discrete state machines, a preprogrammed processor,etc. Control unit 438 preferably controls and orchestrates the functionsperformed by sensor cable 428. Sensor cable 428 also preferablycomprises a sensor 440, e.g., a Hall effect sensor, in circuitcommunication with a pre-amp 442, which in turn is in circuitcommunication with a calibration amplifier 446. Calibration amplifier446 outputs the signal 430 d, which is measured by voltmeter 100.Pre-amp 442 and calibration amplifier 446 may be in circuitcommunication with control unit 438 to provide variable gain control orautomatic gain control to the sensor cable 428. The particularidentification signal 430 c generated by ID generator 436 can be made tochange by control unit 438 depending on a particular gain setting. Forexample, if the sensor 440 is a Hall effect sensor and the sensor cable428 implements a current probe, the particular identification signal 430c generated by ID generator 436 can be set to one voltage value for anampere range of e.g. 0-10 Amperes and set to a different voltage valuefor an ampere range of e.g. 0-1000 Amperes, thereby specificallyidentifying each mode for the probe and maximizing the dynamic range ofthe signal 46 for each application. In this type of system, theprocessor 42 would need to identify the type of cable attached beforeeach measurement or periodically or in response to user input.

[0068] Referring now to FIG. 9 in the context of the previous figures, avery high-level flow chart 500 for the operation of tester 10 is shown.The tasks in the various flow charts are preferably controlled byprocessor 42, which has preferably been preprogrammed with code toimplement the various functions described herein. The flow charts ofFIGS. 9-12 are based on a tester 10 having a hippo clip cable 128connected to an extender cable 228, which in turn is connected to tester10 at connector J1. Starting at task 502, the user first powers up thetester 10 at task 504 by connecting the tester 10 to a battery of astarting/charging system 11. If the tester 10 is to be powered byinternal battery 62, the user presses and holds the button 21 until theprocessor 42 latches the battery 62, as described above. In response tothe system powering up, the processor 42 initializes the tester 10,e.g., by performing various self-tests and/or calibrations, such asautozeroing, described above.

[0069] Next, at task 506, the tester 10 detects the type of cable 28attached to connector J1, e.g., as being one of the cables 128, 228,328, or 428, discussed above. In general, this is done by having theprocessor measure the voltage at node 92 using a successiveapproximation technique with DAC 80 and comparator 82 a, comparing themeasured value of the voltage at node 92 to a plurality of voltagevalues, and selecting a cable type based on the measured voltagerelative to the predetermined voltage values. One or more of theplurality of voltage values may depend on, or be a function of, batteryvoltage; therefore, the processor may measure the battery voltage andperform various computations thereon as part of determining theplurality of voltage values such as, for example, those described inconnection with FIGS. 5A-7B, above. Then, the user tests thestarting/charging system 11, at task 508, and the testing ends at task510.

[0070] Referring now to FIG. 10, a medium-level flow chart is presentedshowing a preferred program flow for the testing of thestarting/charging system and also showing some of the beneficial aspectsof the user interface according to the present invention. The testroutine 508 preferably performs a starter test, a plurality of chargertests, and a diode ripple test. The tester 10 preferably accepts inputfrom the user (e.g., by detecting various keys being pressed) to allowthe user to look over results of tests that have already been performedand to either skip or redo tests that have already been performed. Ingeneral, preferably the user presses one key to begin a test or completea test or to indicate to the processor 42 that the vehicle has beenplaced into a particular state. The user presses a second key to look atthe results of previously completed tests and the user presses a thirdkey to skip tests that have already been performed. Code implementingthe user interface preferably conveys to the user via the display 24whether a test may be skipped or not. More specifically to theembodiment shown in the figures, the user presses the star button 18 tocause the processor to begin a test or complete a test or to indicate tothe processor 42 that the vehicle has been placed into a particular teststate, thereby prompting the processor to take one or more measurements.After one or more tests are performed, the user may press the up button19 to review the results of tests that have been performed. Thereafter,the user may skip or redo tests that have already been done. The usermay skip a test that has already been done by pressing the down button20.

[0071] More particular to FIG. 10, starting at 520, the routine 508first performs the starter test, at 522. As will be explained below inthe text describing FIGS. 11 and 12, for the various tests the user isprompted via the display 24 to place the vehicle into a particular stateand to press a key when the vehicle is in that state, then the tester 10takes one or more measurements, then the data is processed, and thentest results are displayed to the user via display 24.

[0072] In the preferred embodiment, there are five test states: astarter test state 522, a first charger test state 524, a second chargertest state 526, a third charger test state 528, and a diode ripple teststate 530. The tester successively transitions from one state to thenext as each test is completed. There is also a finished state 531 whichis entered after all of the tests are completed, i.e., after the dioderipple test is completed. For each test, preferably the user is promptedvia the display 24 to place the vehicle into a particular state, theuser presses the star key 18 to indicate that the vehicle is in thatstate, then the tester 10 takes one or more measurements, then the datais processed, then test results are displayed to the user via display24, then the user presses the start key 20 to move to the next test. Aseach test is completed, the processor 42 sets a corresponding flag inmemory indicating that that test has been completed. These flags allowthe code to determine whether the user may skip a test that has alreadybeen performed. As shown, the user presses the star key 18 to move tothe next test. As shown in FIG. 10, if the user presses the down key 20while in any of the various states, the code tests whether that test hasbeen completed, at 532 a-532 e. If so, the code branches to the nextstate via branches 534 a-534 e. If not, the code remains in that stateas indicated by branches 536 a-536 e. If the user presses the up key 19,while in any of states 524-530, the code branches to the previous teststate, as indicated by branches 538 a-538 e. Thus, the user may use theup key 19 to look at previously performed tests, and selectively useeither (a) the down key 20 to skip (keep the previously recorded datarather than collecting new data) any particular test that has beenperformed or (b) the star key 18 to redo any particular test that hasalready been performed. For example, assume that a vehicle has passedthe Starter Test 522, failed Charger Test No. 1 524, passed Charger TestNo. 2 526, and passed Charger Test No. 3 528. In this situation, theuser may want to redo Charger Test No. 1 without having to redo theother two tests. In that case, the user may hit the up key 19 twice tomove from state 528 to the Charger Test No. 1, which is state 524. Inthat state, the user may perform Charger Test No. 1 again. Afterperforming Charger Test No. 1 again, the user may move to the next test,the Diode Ripple Test 530, by actuating the down key twice (if in state526) or thrice (if still in state 524), thereby skipping the ChargerTest No. 2 and Charger Test No. 3 and retaining the previously collecteddata for those tests.

[0073] After all the tests are complete, the tester 10 enters the AllTests Complete state 531. While in this state, the user may actuate theup key 19 to view one or more previously completed tests or may actuatethe star key 18 to return, at 540.

[0074] Referring now to FIGS. 11A-11D and 12, additional aspects of theroutines discussed in connection with FIG. 10 are shown. FIGS. 11A-11Dare set up similarly to FIG. 10; however, the symbols representing thedecisions at 532 a-532 e and branches at 536 a-536 e in FIG. 10 havebeen compressed to conserve space in FIGS. 11A-11D. FIGS. 11A-11D focuson the user interface of the present invention and provide additionalinformation about the various tests. FIG. 12 provides additionalinformation about the starter test while de-emphasizing the userinterface. The small diamonds extending to the right from the various“down arrow” boxes in FIGS. 11A-11D represent those decisions 532 a-532e and branches back to the same state 536 a-536 e, as will be furtherexplained below;

[0075] Starting at 600 in FIG. 11A, the test routine 508 first promptsthe user at 602 to turn the engine off and to press the star key 18 whenthat has been done. The user pressing the star key 18 causes the code tobranch at 604 to the next state at 606. At state 606, the user isprompted to either start the engine of the vehicle under test or pressthe star key 18 to abort the starter test, causing the code to branch at608 to the next state at 610.

[0076] While in state 610, the tester 10 repeatedly tests for the starkey 18 being actuated and tests for a drop in the battery voltageindicative of the starter motor starting to crank, as further explainedin the text accompanying FIG. 12. If an actuation of the star key 18 isdetected, the code branches at 611 and the starter test is aborted, at612. If a voltage drop indicative of the start of cranking is detected,the tester 10 collects cranking voltage data with voltmeter 100, asfurther explained in the text accompanying FIG. 12. If the averagecranking voltage is greater than 9.6 VDC, then the cranking voltage isdeemed to be “OK” no matter what the temperature is, the code branchesat 618, sets a flag indicating that the cranking voltage during startingwas “OK” at 620, sets a flag indicating that the starter test has beencompleted at 622, and the corresponding message is displayed at 624. Onthe other hand, if the average cranking voltage is less than 8.5 VDC,then the battery voltage during starting (“cranking voltage”) is deemedto be “Low” no matter what the temperature is, i.e., there might beproblems with the starter, the code branches at 630, sets a flagindicating that the cranking voltage during starting was “Low” at 632,sets a Starter Test Complete Flag indicating that the starter test hasbeen completed at 622, and the corresponding message is displayed at624. Finally, if the average cranking voltage is between 8.5 VDC and 9.6VDC, then the processor 42 needs temperature information to make adetermination as to the condition of the starter, and the code branchesat 633. Accordingly, the processor 42 at step 634 prompts the user withrespect to the temperature of the battery with a message via display 24such as, “Temperature above xx°?” where xx is a threshold temperaturecorresponding to the average measured cranking voltage. A sample tableof cranking voltages and corresponding threshold temperatures is foundat 954 in FIG. 12. On the one hand, if the user indicates that thebattery temperature is above the threshold temperature, then the codebranches at 636, sets a flag indicating that the cranking voltage duringstarting was “Low” at 632, sets the Starter Test Complete Flagindicating that the starter test has been completed at 622, and acorresponding “Low” message is displayed at 624. On the other hand, ifthe user indicates that the battery temperature is not above thethreshold temperature, then the code branches at 638, sets a flagindicating that the cranking voltage during starting was “OK” at 620,sets the Starter Test Complete Flag indicating that the starter test hasbeen completed at 622, and a corresponding “OK” message is displayed at624. While in state 624, if the user presses the star key 18, the codebranches at 660 to state 662.

[0077] The No Load/Curb Idle charger test begins at state 662, in whichthe user is prompted to adjust the vehicle so that the starting/chargingsystem is in a No Load/Curb Idle (NLCI) condition, e.g., very few if anyuser-selectable loads are turned on and no pressure is being applied tothe accelerator pedal. The battery voltage of the vehicle while in theNLCI condition provides information about the condition of theregulator's ability to regulate at its lower limit; the battery voltagewith the vehicle in the NLCI condition should be within a particularrange. Once the user has adjusted the vehicle to be in this condition,the user presses the star key 18, causing the code to branch at 664 totask 668 in which the tester 10 measures the battery voltage usingvoltmeter 100. The battery voltage may be measured once or measured anumber of times and then averaged or summed. It is preferably measured aplurality of times and averaged. In either event, a determination ismade as to whether the battery voltage (or average or sum) is within anacceptable range while in the NLCI condition. The end points of thisrange are preferably determined as functions of battery base voltage(battery voltage before the vehicle was started), V_(b). These endpointsare preferably calculated by adding fixed values to the base voltageV_(b), e.g., V_(low)=V_(b)+0.5 VDC and V_(high)=15 VDC. In thealternative, these endpoints can be determined by performing anothermathematical operation with respect to the base voltage V_(b), e.g.,taking fixed percentages of the base voltage V_(b). The range selectedfor the embodiment shown in the figures is between V_(b)+0.5 VDC andV_(b)=15 VDC. If the battery voltage (or average or sum) is betweenthose endpoints with the vehicle in the NLCI condition, then theregulator is probably in an acceptable condition with respect to itslower limit of regulation. If the battery voltage (or average or sum) isless than V_(b)+0.5 VDC with the vehicle in the NLCI condition, then thebattery voltage (or average or sum) is lower than acceptable and/orexpected. If the battery voltage (or average or sum) is greater thanV_(b)=15 VDC with the vehicle in the NLCI condition, then the batteryvoltage (or average or sum) is higher than acceptable and/or expected.The code continues at 670 to task 672, where a NLCI Test Complete Flagis set indicating that the NLCI test has been performed. Then at 674,the code continues to state 676, in which the results of the NLCI testare displayed. Preferably, the following information is displayed toallow the user to make a determination as to whether the regulator is inan acceptable condition: base battery voltage and the battery voltagewith the vehicle in the NLCI condition. Also, if the battery voltagewith the vehicle in the NLCI condition was below the acceptable/expectedrange, a “Low” indication is presented to the user near the test batteryvoltage. Similarly, if the battery voltage with the vehicle in the NLCIcondition was above the acceptable/expected range, a “Hi” indication ispresented to the user near the test battery voltage. With thisinformation, the user can make a determination as to whether theregulator is in an acceptable condition with respect to its lowerregulation limit. While in state 676, if the user presses the star key18, the code branches at 678 to state 690.

[0078] The No Load/Fast Idle charger test begins at state 690, in whichthe user is prompted to adjust the vehicle so that the starting/chargingsystem is in a No Load/Fast Idle (NLFI) condition, e.g., very few if anyuser-selectable loads are turned on and pressure is being applied to theaccelerator pedal to cause the vehicle motor to operate at about 2000revolutions per minute (RPM). The battery voltage of the vehicle whilein the NLFI condition provides information about the condition of theregulator's ability to regulate at its upper limit; the battery voltagewith the vehicle in the NLFI condition should be within a particularrange. Once the user has adjusted the vehicle to be in this condition,the user presses the star key 18, causing the code to branch, at 692, totask 694 in which the tester 10 measures the battery voltage usingvoltmeter 100. The battery voltage may be measured once or measured anumber of times and then averaged or summed. Preferably it is measured anumber of times and then averaged. In either event, a determination ismade as to whether the battery voltage (or average or sum) is within anacceptable range while in the NLFI condition. The end points of thisrange are preferably determined as functions of battery base voltage(battery voltage before the vehicle was started), V_(b). These endpointsare preferably calculated by adding fixed values to the base voltageV_(b), e.g., V_(low)=V_(b)+0.5 VDC and V_(high)=15 VDC. In thealternative, these endpoints can be determined by performing anothermathematical operation with respect to the base voltage V_(b), e.g.,taking fixed percentages of the base voltage V_(b). The range selectedfor the embodiment shown in the figures is between V_(b)+0.5 VDC andV_(b)=15 VDC. If the battery voltage (or average or sum) is betweenthose endpoints with the vehicle in the NLFI condition, then theregulator is probably in an acceptable condition with respect to itsupper limit of regulation. If the battery voltage (or average or sum) isless than V_(b)+0.5 VDC with the vehicle in the NLFI condition, then thebattery voltage (or average or sum) is lower than acceptable and/orexpected. If the battery voltage (or average or sum) is greater thanV_(b)=15 VDC with the vehicle in the NLFI condition, then the batteryvoltage (or average or sum) is higher than acceptable and/or expected.The code continues at 696 to task 698, where a NLFI Test Complete Flagis set indicating that the NLFI test has been performed. Then at 700,the code continues to state 702, in which the results of the NLFI testare displayed. Preferably, the following information is displayed toallow the user to make a determination as to whether the regulator is inan acceptable condition: base battery voltage (battery voltage beforethe vehicle was started) and the battery voltage with the vehicle in theNLFI condition. Also, if the battery voltage with the vehicle in theNLFI condition was below the acceptable/expected range, a “Low”indication is presented to the user near the test battery voltage.Similarly, if the battery voltage with the vehicle in the NLFI conditionwas above the acceptable/expected range, a “Hi” indication is presentedto the user near the test battery voltage. With this information, theuser can make a determination as to whether the regulator is in anacceptable condition with respect to its upper regulation limit. Whilein state 702, if the user presses the star key 18, the code branches at704 to state 720.

[0079] The Full Load/Fast Idle charger test begins at state 720, inwhich the user is prompted to adjust the vehicle so that thestarting/charging system is in a Full Load/Fast Idle (FLFI) condition,e.g., most if not all user-selectable loads (lights, blower(s), radio,defroster, wipers, seat heaters, etc.) are turned on and pressure isbeing applied to the accelerator pedal to cause the vehicle motor tooperate at about 2000 RPM. The battery voltage of the vehicle while inthe FLFI condition provides information about the condition of thealternator with respect to its power capacity; the battery voltage withthe vehicle in the FLFI condition should be within a particular range.Once the user has adjusted the vehicle to be in this condition, the userpresses the star key 18, causing the code to branch, at 722, to task 724in which the tester 10 measures the battery voltage using voltmeter 100.The battery voltage may be measured once or measured a number of timesand then averaged or summed. Preferably it is measured a number of timesand then averaged. In either event, a determination is made as towhether the battery voltage (or average or sum) is within an acceptablerange while in the FLFI condition. The end points of this range arepreferably determined as functions of battery base voltage (batteryvoltage before the vehicle was started), V_(b). These endpoints arepreferably calculated by adding fixed values to the base voltage V_(b),e.g., V_(low)=V_(b)+0.5 VDC and V_(high)=15 VDC. In the alternative,these endpoints can be determined by performing another mathematicaloperation with respect to the base voltage V_(b), e.g., taking fixedpercentages of the base voltage V_(b). The range selected for theembodiment shown in the figures is between V_(b)+0.5 VDC and V_(b)=15VDC. If the battery voltage (or average or sum) is between thoseendpoints with the vehicle in the FLFI condition, then the alternator isprobably in an acceptable condition with respect to its power capacity.If the battery voltage (or average or sum) is less than V_(b)+0.5 VDCwith the vehicle in the FLFI condition, then the battery voltage (oraverage or sum) is lower than acceptable and/or expected. If the batteryvoltage (or average or sum) is greater than V_(b)=15 VDC with thevehicle in the FLFI condition, then the battery voltage (or average orsum) is higher than acceptable and/or expected. The code continues at726 to task 728, where a FLFI Test Complete Flag is set indicating thatthe FLFI test has been performed. Then at 730, the code continues tostate 732, in which the results of the FLFI test are displayed.Preferably, the following information is displayed to allow the user tomake a determination as to whether the alternator is in an acceptablecondition: base battery voltage (battery voltage before the vehicle wasstarted) and the battery voltage with the vehicle in the FLFI condition.Also, if the battery voltage with the vehicle in the FLFI condition wasbelow the acceptable/expected range, a “Low” indication is presented tothe user near the test battery voltage. Similarly, if the batteryvoltage with the vehicle in the FLFI condition was above theacceptable/expected range, a “Hi” indication is presented to the usernear the test battery voltage. With this information, the user can makea determination as to whether the alternator is in an acceptablecondition with respect to its power capacity. While in state 732, if theuser presses the star key 18, the code branches at 734 to state 750.

[0080] The alternator diode ripple test begins at state 750, in whichthe user is prompted to adjust the vehicle so that the starting/chargingsystem is in a Medium Load/Low Idle (MLLI) condition, e.g., the lightsare on, but all other user-selectable loads (blower(s), radio,defroster, wipers, seat heaters, etc.) are turned off and pressure isbeing applied to the accelerator pedal to cause the vehicle motor tooperate at about 1000 RPM. For the diode ripple test, the diode ripplecircuit 102 is used and the processor measures the diode ripple voltageat 114 at the output of the peak detect circuit 112. The diode ripplevoltage with the vehicle while in the MLLI condition providesinformation about the condition of the diodes in the alternator with aknown load (most vehicle lights draw about 65 Watts of power per lamp).The diode ripple voltage 114 with the vehicle in the MLLI conditionshould be less than a predetermined threshold, e.g., for the circuit ofFIG. 4B less than 1.2 VDC for a 12-volt system and less than 2.4 VDC fora 24-volt system. Once the user has adjusted the vehicle to be in thiscondition, the user presses the star key 18, causing the code to branch,at 752, to task 754 in which the tester 10 measures the ripple voltageusing ripple circuit 102. The ripple voltage 114 may be measured once ormeasured a number of times and then averaged or summed. Preferably it ismeasured a number of times and then averaged. In either event, adetermination is made as to whether the ripple voltage 114 (or averageor sum) is less than the acceptable threshold while in the MLLIcondition. The threshold ripple voltage selected for the embodimentshown in FIG. 4B is 1.2 VDC for a 12-volt system and 2.4 VDC for a24-volt system. If the ripple voltage 114 is lower than that thresholdwith the vehicle in the MLLI condition, then the alternator diodes areprobably in an acceptable condition. The code continues at 756 to task758, where a Diode Ripple Test Complete Flag is set indicating that thediode ripple test has been performed. Then at 760, the code continues tostate 762, in which the results of the diode ripple test are displayed.Preferably, either a ripple voltage “OK” or ripple voltage “Hi” messageis displayed, depending on the measured ripple voltage relative to thethreshold ripple voltage. With this information, the user can make adetermination as to whether the alternator diodes are in an acceptablecondition. While in state 762, if the user presses the star key 18, thecode branches at 764 to state 770.

[0081] State 770 an extra state in that it is not a separate test of thestarting/charging system 11. As shown in FIG. 10 and discussed in theaccompanying text, the user may use the up key 19 (up button) and thedown key 20 (down button) to review the results of past tests, to redopreviously performed tests and/or skip (keep the data for) previouslyperformed tests. One implementation of this feature of the userinterface is shown in more detail in FIGS. 11A-11D. State 770 providesthe user with a state between the results of the last test and exitingthe test portion of the code so that the user can use the up key 19 anddown key 20 to review previous test results and skip and/or redo some ofthe tests. Pressing the star key 18 while in state 770 causes the codeto end, i.e., return, at 772.

[0082] While in state 602, in which the user is prompted to turn theengine off, pressing the up key 19 does nothing (?please confirm). Whilein state 602, if the Starter Test has already been performed, i.e., ifthe Starter Test Complete Flag is set, e.g., at task 672, the displayconveys to the user that the down key 20 is active, e.g., by displayingan image corresponding to that key, such as an image of a downwardlypointing arrow. FIG. 13 shows a number of screens for display 26 showingthis feature of the user interface. Screen 1000 of FIG. 13 shows adisplay of a Starter Test prompt, before the Starter Test has beenperformed, i.e., with the Starter Test Complete Flag cleared. Screen1002 of FIG. 13 shows a display of the same Starter Test prompt, withthe Starter Test Complete Flag set, i.e., after the Starter Test hasbeen performed at least once since the tester 10 was last powered up.Note the presence of down arrow 1004 in screen 1002 that is not inscreen 1000, indicating that the down arrow key is active and may beused to skip the Starter Test.

[0083] Thus, while in state 602, pressing the down key 20 causes thecode to branch to a decision at 780 as to whether the Starter Test hasalready been performed, i.e., whether the Starter Test Complete Flag isset. If the down key 20 is pressed while the Starter Test Complete Flagis not set, the code remains in state 602 and waits for the user topress the star key 18, which will cause the Starter Test to be redone,starting with branch 604. If the down key 20 is pressed while theStarter Test Complete Flag is set, the code branches at 782 to state624, discussed above, in which the results of the Starter Test aredisplayed. Thus, from state 602, if the Starter Test has already beenperformed, the user may redo that test by pressing the star key 18, ormay skip the test (thereby retaining the data and results from theprevious execution of that test) by pressing the down key 20.

[0084] While in state 606, in which the user is prompted to start theengine, pressing the up key 19 causes the code to branch at 784 back tostate 602, discussed above. While in state 606, if the Starter Test hasalready been performed, i.e., if the Starter Test Complete Flag is set,e.g., at task 622, the display conveys to the user that the down key 20is active, e.g., by displaying an image corresponding to that key, suchas an image of a downwardly pointing arrow (e.g., down arrow 1004 in thescreen shots in FIG. 13). While in state 606, pressing the down key 20causes the code to branch to a decision at 786 as to whether the StarterTest has already been performed, i.e., whether the Starter Test CompleteFlag is set. If the down key 20 is pressed while the Starter TestComplete Flag is not set, the code remains in state 606 and waits forthe comparator 82 b (FIGS. 2 and 4A) to detect a crank and waits for theuser to press the star key 18, which will exit the Starter Test 612 viabranch 611. If the down key 20 is pressed while the Starter TestComplete Flag is set, the code branches at 788 to state 624, discussedabove, in which the results of the Starter Test are displayed. Thus,from state 606, the user may back up to the previous step by pressingthe up key 19 and, if the Starter Test has already been performed, theuser may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

[0085] While in state 624, in which the results of the Starter Test arepresented to the user, pressing the up key 19 causes the code to branchat 790 to a decision at 792 as to whether the user was prompted to entera battery temperature during the Starter Test, i.e., whether the batteryvoltage measured during cranking is between 8.5 VDC and 9.6 VDC andtherefore battery temperature is relevant to the cranking voltagedetermination. If so, the code branches at 794 to state 634, discussedabove, in which the user is prompted to enter data with respect tobattery temperature. If not, the code branches at 796 to state 606,discussed above, in which the user is prompted to start the engine.While in state 624, if the NLCI Test has already been performed, i.e.,if the NLCI Test Complete Flag is set, e.g., at task 672, the displayconveys to the user that the down key 20 is active, e.g., by displayingan image corresponding to that key, such as an image of a downwardlypointing arrow. Screen 1006 of FIG. 13 shows a display of the results ofa hypothetical Starter Test before the NLCI Test has been performed,i.e., with the NLCI Test Complete Flag cleared. Screen 1008 of FIG. 13shows a display of the same Starter Test results, with the NLCI TestComplete Flag set, i.e., after the NLCI Test has been performed at leastonce since the tester 10 was last powered up. Note the presence of downarrow 1004 in screen 1008 that is not in screen 1006, indicating thatthe down arrow key is active and may be used to skip to the results ofthe NLCI Test.

[0086] Thus, while in state 624, pressing the down key 20 causes thecode to branch to a decision at 800 as to whether the NLCI Test hasalready been performed, i.e., whether the NLCI Test Complete Flag isset. If the down key 20 is pressed while the NLCI Test Complete Flag isnot set, the code remains in state 624 and waits for the user to pressthe star key 18, which will cause the code to branch to the beginning ofthe NLCI Test, via branch 660. If the down key 20 is pressed while theNLCI Test Complete Flag is set, the code branches at 802 to state 676,discussed above, in which the results of the NLCI Test are displayed.Thus, from state 624, the user may back up to the previous step(s) bypressing the up key 19 and, if the NLCI Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

[0087] While in state 662, which is the start of the NLCI Test, pressingthe up key 19 causes the code to branch at 804 to state 624, discussedabove, in which the results of the Starter Test are presented. While instate 662, if the NLCI Test has already been performed, i.e., if theNLCI Test Complete Flag is set, e.g., at task 672, the display conveysto the user that the down key 20 is active, e.g., by displaying an imagecorresponding to that key, such as an image of a downwardly pointingarrow (e.g., down arrow 1004 in the screen shots in FIG. 13). While instate 662, pressing the down key 20 causes the code to branch to adecision at 806 as to whether the NLCI Test has already been performed,i.e., whether the NLCI Test Complete Flag is set. If the down key 20 ispressed while the NLCI Test Complete Flag is not set, the code remainsin state 662 and waits for the user to press the star key 18, which willcause the code to take a measurement of battery voltage, via branch 664.If the down key 20 is pressed while the NLCI Test Complete Flag is set,the code branches at 808 to state 676, discussed above, in which theresults of the NLCI Test are displayed. Thus, from state 662, the usermay back up to the previous test step (the end of the Starter Test) bypressing the up key 19 and, if the NLCI Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

[0088] While in state 676, in which the results of the NLCI Test arepresented to the user, pressing the up key 19 causes the code to branchat 810 to state 662, discussed above, in which the user is prompted toadjust the vehicle into the NLCI condition. While in state 676, if theNLFI Test has already been performed, i.e., if the NLFI Test CompleteFlag is set, e.g., at task 698, the display conveys to the user that thedown key 20 is active, e.g., by displaying an image corresponding tothat key, such as an image of a downwardly pointing arrow. Screen 1010of FIG. 13 shows a display of the results of a hypothetical NLCI Testbefore the NLFI Test has been performed, i.e., with the NLFI TestComplete Flag cleared. Screen 1012 of FIG. 13 shows a display of thesame NLCI Test results, with the NLFI Test Complete Flag set, i.e.,after the NLFI Test has been performed at least once since the tester 10was last powered up. Note the presence of down arrow 1004 in screen 1012that is not in screen 1010, indicating that the down arrow key is activeand may be used to skip to the results of the NLFI Test.

[0089] Thus, while in state 676, pressing the down key 20 causes thecode to branch to a decision at 812 as to whether the NLFI Test hasalready been performed, i.e., whether the NLFI Test Complete Flag isset. If the down key 20 is pressed while the NLFI Test Complete Flag isnot set, the code remains in state 676 and waits for the user to pressthe star key 18, which will cause the code to branch to the beginning ofthe NLFI Test, via branch 678. If the down key 20 is pressed while theNLFI Test Complete Flag is set, the code branches at 814 to state 702,discussed above, in which the results of the NLFI Test are displayed.Thus, from state 676, the user may back up to the previous step (state662) by pressing the up key 19 and, if the NLFI Test has already beenperformed, the user may redo that test by pressing the star key 18, ormay skip the test (thereby retaining the data and results from theprevious execution of that test) by pressing the down key 20.

[0090] While in state 690, which is the start of the NLFI Test, pressingthe up key 19 causes the code to branch at 816 to state 676, discussedabove, in which the results of the NLCI Test are presented. While instate 690, if the NLFI Test has already been performed, i.e., if theNLFI Test Complete Flag is set, e.g., at task 698, the display conveysto the user that the down key 20 is active, e.g., by displaying an imagecorresponding to that key, such as an image of a downwardly pointingarrow (e.g., down arrow 1004 in the screen shots in FIG. 13). While instate 690, pressing the down key 20 causes the code to branch to adecision at 820 as to whether the NLFI Test has already been performed,i.e., whether the NLFI Test Complete Flag is set. If the down key 20 ispressed while the NLFI Test Complete Flag is not set, the code remainsin state 690 and waits for the user to press the star key 18, which willcause the code to take a measurement of battery voltage, via branch 692.If the down key 20 is pressed while the NLFI Test Complete Flag is set,the code branches at 822 to state 702, discussed above, in which theresults of the NLFI Test are displayed. Thus, from state 690, the usermay back up to the previous test step (the end of the NLCI Test) bypressing the up key 19 and, if the NLFI Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

[0091] While in state 702, in which the results of the NLFI Test arepresented to the user, pressing the up key 19 causes the code to branchat 824 to state 690, discussed above, in which the user is prompted toadjust the vehicle into the NLFI condition. While in state 702, if theFLFI Test has already been performed, i.e., if the FLFI Test CompleteFlag is set, e.g., at task 728, the display conveys to the user that thedown key 20 is active, e.g., by displaying an image corresponding tothat key, such as an image of a downwardly pointing arrow. Screen 1014of FIG. 13 shows a display of the results of a hypothetical NLFI Testbefore the FLFI Test has been performed, i.e., with the FLFI TestComplete Flag cleared. Screen 1016 of FIG. 13 shows a display of thesame NLFI Test results, with the FLFI Test Complete Flag set, i.e.,after the FLFI Test has been performed at least once since the tester 10was last powered up. Note the presence of down arrow 1004 in screen 1016that is not in screen 1014, indicating that the down arrow key is activeand may be used to skip to the results of the FLFI Test.

[0092]91 Thus, while in state 702, pressing the down key 20 causes thecode to branch to a decision at 830 as to whether the FLFI Test hasalready been performed, i.e., whether the FLFI Test Complete Flag isset. If the down key 20 is pressed while the FLFI Test Complete Flag isnot set, the code remains in state 702 and waits for the user to pressthe star key 18, which will cause the code to branch to the beginning ofthe FLFI Test, via branch 704. If the down key 20 is pressed while theFLFI Test Complete Flag is set, the code branches at 832 to state 732,discussed above, in which the results of the FLFI Test are displayed.Thus, from state 702, the user may back up to the previous step (state690) by pressing the up key 19 and, if the FLFI Test has already beenperformed, the user may redo that test by pressing the star key 18, ormay skip the test (thereby retaining the data and results from theprevious execution of that test) by pressing the down key 20.

[0093] While in state 720, which is the start of the FLFI Test, pressingthe up key 19 causes the code to branch at 834 to state 702, discussedabove, in which the results of the NLFI Test are presented. While instate 720, if the FLFI Test has already been performed, i.e., if theFLFI Test Complete Flag is set, e.g., at task 728, the display conveysto the user that the down key 20 is active, e.g., by displaying an imagecorresponding to that key, such as an image of a downwardly pointingarrow (e.g., down arrow 1004 in the screen shots in FIG. 13). While instate 720, pressing the down key 20 causes the code to branch to adecision at 840 as to whether the FLFI Test has already been performed,i.e., whether the FLFI Test Complete Flag is set. If the down key 20 ispressed while the FLFI Test Complete Flag is not set, the code remainsin state 720 and waits for the user to press the star key 18, which willcause the code to take a measurement of battery voltage, via branch 722.If the down key 20 is pressed while the FLFI Test Complete Flag is set,the code branches at 842 to state 732, discussed above, in which theresults of the FLFI Test are displayed. Thus, from state 720, the usermay back up to the previous test step (the end of the NLFI Test) bypressing the up key 19 and, if the FLFI Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

[0094] While in state 732, in which the results of the FLFI Test arepresented to the user, pressing the up key 19 causes the code to branchat 844 to state 720, discussed above, in which the user is prompted toadjust the vehicle into the FLFI condition. While in state 732, if theDiode Ripple Test has already been performed, i.e., if the Diode RippleTest Complete Flag is set, e.g., at task 758, the display conveys to theuser that the down key 20 is active, e.g., by displaying an imagecorresponding to that key, such as an image of a downwardly pointingarrow. Screen 1018 of FIG. 13 shows a display of the results of ahypothetical FLFI Test before the Diode Ripple Test has been performed,i.e., with the Diode Ripple Test Complete Flag cleared. Screen 1020 ofFIG. 13 shows a display of the same FLFI Test results, with the DiodeRipple Test Complete Flag set, i.e., after the Diode Ripple Test hasbeen performed at least once since the tester 10 was last powered up.Note the presence of down arrow 1004 in screen 1020 that is not inscreen 1018, indicating that the down arrow key is active and may beused to skip to the results of the Diode Ripple Test.

[0095] Thus, while in state 732, pressing the down key 20 causes thecode to branch to a decision at 850 as to whether the Diode Ripple Testhas already been performed, i.e., whether the Diode Ripple Test CompleteFlag is set. If the down key 20 is pressed while the Diode Ripple TestComplete Flag is not set, the code remains in state 732 and waits forthe user to press the star key 18, which will cause the code to branchto the beginning of the Diode Ripple Test, via branch 734. If the downkey 20 is pressed while the Diode Ripple Test Complete Flag is set, thecode branches at 852 to state 762, discussed above, in which the resultsof the Diode Ripple Test are displayed. Thus, from state 732, the usermay back up to the previous step (state 720) by pressing the up key 19and, if the Diode Ripple Test has already been performed, the user mayredo that test by pressing the star key 18, or may skip the test(thereby retaining the data and results from the previous execution ofthat test) by pressing the down key 20.

[0096] While in state 750, which is the start of the Diode Ripple Test,pressing the up key 19 causes the code to branch at 854 to state 732,discussed above, in which the results of the FLFI Test are presented.While in state 750, if the Diode Ripple Test has already been performed,i.e., if the Diode Ripple Test Complete Flag is set, e.g., at task 758,the display conveys to the user that the down key 20 is active, e.g., bydisplaying an image corresponding to that key, such as an image of adownwardly pointing arrow (e.g., down arrow 1004 in the screen shots inFIG. 13). While in state 750, pressing the down key 20 causes the codeto branch to a decision at 860 as to whether the Diode Ripple Test hasalready been performed, i.e., whether the Diode Ripple Test CompleteFlag is set. If the down key 20 is pressed while the Diode Ripple TestComplete Flag is not set, the code remains in state 750 and waits forthe user to press the star key 18, which will cause the code to take ameasurement of battery voltage, via branch 752. If the down key 20 ispressed while the Diode Ripple Test Complete Flag is set, the codebranches at 862 to state 762, discussed above, in which the results ofthe Diode Ripple Test are displayed. Thus, from state 750, the user mayback up to the previous test step (the end of the FLFI Test) by pressingthe up key 19 and, if the Diode Ripple Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

[0097] While in state 762, in which the results of the Diode Ripple Testare presented to the user, pressing the up key 19 causes the code tobranch at 864 to state 750, discussed above, in which the user isprompted to adjust the vehicle into the Diode Ripple condition. While instate 762, the display conveys to the user that the down key 20 isactive, e.g., by displaying an image corresponding to that key, such asan image of a downwardly pointing arrow. Screen 1022 of FIG. 13 shows adisplay of the results of a hypothetical Diode Ripple Test. Note thepresence of down arrow 1004 in screen 1022, indicating that the downarrow key is active and may be used to skip to the last state 770. Thus,while in state 762, pressing the down key 20 causes the code to branchvia branch 866 to state 770. Thus, from state 762, the user may back upto the previous step (state 750) by pressing the up key 19 and advanceto the next step (state 770) by either pressing the star key 18 or bypressing the down key 20.

[0098] While in state 770, which is All Tests Complete state, pressingthe up key 19 causes the code to branch at 868 back to state 762,discussed above, in which the results of the Diode Ripple Test arepresented. This screen is shown as screen 1024 in FIG. 13.

[0099] Therefore, while in state 770, after all of the tests have beenperformed, it takes twelve (12) presses of the up key 19 to move fromstate 770 back up to the beginning at state 602 (state 770 back to state762 back to state 750 back to state 732 back to state 720 back to state702 back to state 690 back to state 676 back to state 662 back to state624 back to either state 634 or state 606 back to state 602) and takesseven (7) presses of the down key 20 to move back down from state 602 tostate 770 (state 602 down to state 624 down to state 676 down to state702 down to state 732 down to state 762 down to state 770). This userinterface of the present invention greatly facilitates the userreviewing results of and redoing, if necessary, previously performedtests with the tester 10. In the alternative, the tester 10 can be codedso that while in state 770, after all of the tests have been performed,it takes twelve (12) presses of the up key 19 to move from state 770back up to the beginning at state 602, and takes twelve (12) presses ofthe down key 20 to move from state 602 back down to state 770.

[0100] The Starter Test was previously discussed in the context of task522 in FIG. 10 and tasks 602-624 in FIGS. 11A-11B. Referring now to FIG.12, additional information about the Starter Test is provided, focusingmore on the preferred testing method and less on the user interface thanthe previous discussions. The Starter Test begins at task 900 in FIG.12. The Starter Test routine first prompts the user at 902 to turn theengine off and to press the star key 18 when that has been done. Theuser pressing the star key 18 causes the code to branch at 904 to thenext task 906, in which the base battery voltage V_(b) is measured usingthe voltmeter circuit 100. Additionally, a crank threshold voltageV_(ref) is calculated by subtracting a fixed value from the base voltageV_(b), e.g., V_(ref)=V_(b)−0.5 VDC. In the alternative, the crankthreshold voltage V_(ref) can be determined by performing anothermathematical operation with respect to the base voltage V_(b), e.g.,taking a fixed percentage of the base voltage V_(b). In any event, avalue corresponding to the threshold voltage V_(ref) is transferred fromthe processor 42 to the DAC 80 via bus 81 to cause the DAC 80 to outputthe threshold voltage V_(ref) at output 83 b as one input to comparator82 b. In this state, after the voltage at output 83 b stabilizes, thecomparator 82 b constantly monitors the battery voltage, waiting for thebattery voltage to drop to less than (or less than or equal to) thethreshold level V_(ref).

[0101] Next, at step 908, the user is prompted to either start theengine of the vehicle under test or press the star key 18 to abort thestarter test. Next, via branch 910, the code enters a loop in which theprocessor 42 periodically polls the input corresponding to comparator 82b to determine if the battery voltage has dropped to less than (or lessthan or equal to) the threshold level V_(ref) and periodically polls theinputs corresponding to switches 18-21 to determine if any key has beenpressed. Thus, at decision 912, if the output 85 b of comparator 82 bremains in a HIGH state, the processor tests at 914 whether any key hasbeen pressed. If not, the processor 42 again tests the comparator todetermine whether the comparator has detected a battery voltage drop,and so on. If at test 914 a key press has been detected, the message“Crank Not Detected” is displayed at 916 and the routine ends at 918.

[0102] On the other hand, at decision 912, if the processor 42determines that the output 85 b of comparator 82 b has transitioned froma HIGH state to a LOW state, then the battery voltage has dropped toless than the threshold level V_(ref) and the processor branches via 920to code at 922 that waits a predetermined period of time, preferablybetween about 10 milliseconds and about 60 milliseconds, more preferablyabout 40 milliseconds, and most preferably 40 milliseconds, beforebeginning to sample the battery voltage, i.e., the cranking voltage.Waiting this period of time permits the starter motor to stabilize sothat the measured voltage is a stable cranking voltage and not atransient voltage as the starter motor begins to function. Additionally,the code at 922 also sets a variable N to 1 and preferably displays amessage to the user via display 24, e.g., “Testing.” The variable N isused to track the number of samples of cranking voltage that have beentaken.

[0103] Next at 924 the cranking volts V_(c) are measured using voltmeter100 and the measured cranking voltage is stored by processor 42 asV_(c)(N). Then the most recently measured cranking voltage sampleV_(c)(N) is compared to the value corresponding to the threshold voltageV_(ref) that was previously used at step 912 to determine the start ofthe cranking cycle, at 926. On the one hand, if at 926 the batteryvoltage is still less than V_(ref), then it is safe to assume that thestarter motor is still cranking and the measurement V_(c)(N) representsa cranking voltage. Accordingly, the processor next at 928 determines ifeight (8) samples have been taken. If so, the code branches at 930 totask 932. If not, then N is incremented at 934 and another crankingvoltage sample is taken and stored at 924 and the loop iterates.

[0104] On the other hand, if at 926 the battery voltage has risen to theextent that it is greater than V_(ref), then it is safe to assume thatthe car has started and it is meaningless to continue to measure andstore battery voltage, because the battery voltage samples no longerrepresent a cranking voltage. Accordingly, the processor next at 936tests to determine if only one sample has been collected. If so, thenthe code branches to task 932. If not, then the processor 42 has takenmore than one measurement of battery voltage and one voltage may bediscarded by decrementing N at 938 under the assumption that the Nthsample was measured after the car had started (and thus does notrepresent a cranking voltage), and the code continues to task 932.

[0105] At 932, the N collected cranking voltages are averaged todetermine an average cranking voltage V_(c) ^(avg). At this stage, therest of FIG. 12 is essentially like that shown in FIG. 11A, except thata table of threshold values is set forth in FIG. 12. If the averagecranking voltage V_(c) ^(avg) is greater than 9.6 VDC, then the crankingvoltage is deemed to be “OK” no matter what the temperature is, and thecode branches at 946, displays a corresponding message at 948, and endsat 950. On the other hand, if the average cranking voltage V_(c) ^(avg)is less than 8.5 VDC, then the battery voltage during starting(“cranking voltage”) is deemed to be “Low” no matter what thetemperature is, i.e., there might be problems with the starter, and thecode branches at 940, displays a corresponding message at 942, and endsat 944. Finally, if the average cranking voltage is between 8.5 VDC and9.6 VDC, then the processor 42 needs temperature information to make adetermination as to the starter. Accordingly, the processor 42 at step952 prompts the user with respect to the temperature of the battery witha message via display 24 such as, “Temperature above xx°?” where xx is athreshold temperature corresponding to the average measured crankingvoltage from the table 954 in FIG. 12. For example, if the averagecranking voltage V_(c) ^(avg) is between 9.1 VDC and 9.3 VDC, the useris preferably prompted to enter whether the battery temperature is above30° F. Similarly, if the average cranking voltage V_(c) ^(avg) isbetween 9.3 VDC and 9.4 VDC, the user is preferably prompted to enterwhether the battery temperature is above 40° F. In the alternative, theprocessor 42 can interpolate between the various temperatures in thetable in 954. For example, if the average cranking voltage V_(c) ^(avg)is 9.2 VDC, the user can be prompted to enter whether the batterytemperature is above 35° F. and if the average cranking voltage V_(c)^(avg) is 9.35 VDC, the user can be prompted to enter whether thebattery temperature is above 45° F. On the one hand, if the userindicates that the battery temperature is greater than the thresholdtemperature, then the code branches at 956, displays a correspondingmessage at 942, and ends at 944. On the other hand, if the userindicates that the battery temperature is less than the thresholdtemperature, then the code branches at 958, displays a correspondingmessage at 948, and ends at 950.

[0106] While the present invention has been illustrated by thedescription of embodiments thereof, and while the embodiments have beendescribed in some detail, it is not the intention of the applicant torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. For example, the housing connector J1 can bereplaced with a number of discrete connections, e.g., a number ofso-called “banana plug” receptors, preferably with at least one of thediscrete connections providing a signal to the detection circuitry.Therefore, the invention in its broader aspects is not limited to thespecific details, representative apparatus and methods, and illustrativeexamples shown and described. Accordingly, departures may be made fromsuch details without departing from the spirit or scope of theapplicant's general inventive concept.

What is claimed is:
 1. A hand-held, portable tester for testing astarter/charger system of an internal combustion engine, comprising: (a)an electronic test circuit, said test circuit capable of performing atleast one test on the starting/charging system; (b) a hand-held,portable enclosure housing said electronic test circuit; and (c) ahousing connector providing a first plurality of electrical connections,said housing connector being affixed to said housing and in circuitcommunication with said electronic test circuit, for placing saidelectronic test circuit in circuit communication with thestarter/charger system via a test cable electrically connected to saidhousing connector via a removable cable connector providing a secondplurality of electrical connections.
 2. A hand-held, portable tester fortesting a starter/charger system of an internal combustion engineaccording to claim 1, wherein said electronic test circuit is furthercharacterized by performing a plurality of tests on thestarting/charging system.
 3. A hand-held, portable tester for testing astarter/charger system of an internal combustion engine according toclaim 1, wherein said electronic test circuit is further characterizedby performing at least one test on a starting unit of thestarting/charging system; a plurality of tests on a charging unit of thestarting/charging system, at least one of said tests on the chargingunit of the starting/charging system being a diode ripple test.
 4. Ahand-held, portable tester for testing a starter/charger system of aninternal combustion engine according to claim 1, wherein said electronictest circuit is further characterized by performing at least one test ona starting unit of the starting/charging system; at least four tests ona charging unit of the starting/charging system, at least one of saidtests on the charging unit of the starting/charging system being a dioderipple test.